1. Field of the Invention
The present general inventive concept relates to an ink circulation system and an inkjet recording apparatus. More particularly, the present inventive concept relates to an ink circulation system to perform ink circulation between an ink head, which discharges ink to form an image onto a recording medium, and an ink tank, and an inkjet recording apparatus using the same.
2. Description of the Related Art
An image forming apparatus such as an inkjet printer fires droplets of printing ink onto a printing medium such as a paper sheet or fabric to form an image in a desired color.
A conventional inkjet printer generally includes an ink circulation system which allows the ink to circulate between an ink tank and an ink firing head assembly. FIG. 1 illustrates a general ink circulation system. Referring to FIG. 1, an ink tank 10 (i.e., an ink cartridge) stores printing ink therein, and is connected to a pressure adjusting unit 11. The pressure adjusting unit 11 is connected to a head assembly 12 which fires an ink onto a printing medium to form an image. A pump 14 is provided on an ink circulation path 13 between the head assembly 12 and the ink tank 10.
In the above construction, the pump 14 is driven and negative pressure is generated from the ink tank 10. According to the negative pressure being produced at the ink circulation path 13, ink of the pressure adjusting unit 11 is introduced into the head assembly 12. The pressure adjusting unit 11 usually includes a filter which filters out impurities or bubbles of the fed ink. The ink from the pump 14 is recovered into the ink tank 10. In the meantime, by the negative pressure, the bubbles at the head assembly 12 are moved to the pressure adjusting unit 11 and recovered into the ink tank 10. The negative pressure is exerted by the pressure adjusting unit 11 in the standby mode, such that the ink does not gravitate through a head chip 12a of the head assembly 12.
In the general ink circulation system as explained above, due to a resistance of the filter housed inside the pressure adjusting unit 11, it is difficult to recover the bubbles of the head assembly 12 back to the ink tank 10, which causes inefficient ink circulation. As a result, an amount of ink charged in the head assembly 12 is unsatisfactory, thereby causing inefficient ink firing and image quality degradation.
Also the ink circulation system as illustrated in FIG. 1 is not capable of purging, which removes bubbles not only from the head assembly 12, but also from the nozzles of the head chip 12a. 